Re: iSCSI: multiple sessions b/n a pair of WWUIs.

[Pierre Labat <pierre_labat@hp.com>]

John Hufferd wrote:

> Santosh,
> I think I am beginning to see the problem.  A given iSCSI Initiator Port
> can NOT have a second session with the same iSCSI Initiator Port and be
> consistent with SCSIness.  The second session could be started with another
> ISID, (to the same iSCSI Target Port) but if the session was established it
> would not have any of its commands and data handled via any techniques
> defined by SCSI or iSCSI.  In fact its use would require a wedge driver.
> This is the exact confusion I was trying to avoid.  Technically if you were
> actually able to start another Session to the same Target Port, it would
> be, by definition another iSCSI Initiator Port.   The two different Ports
> would need to be coordinated by what we have been calling a Wedge Driver.
>
> Today, the way we use multiple Fibre Channel Initiator Ports connected to
> the same Fibre Channel Target Ports is by use of Wedge Drivers.  I think
> what you are suggesting causes the need for a Wedge Drivers to integrate
> the iSCSI Initiator Ports.  Not sure that we want to cause this type of
> thinking, by accident.  One of the reasons for Multiple Connections per
> Session was to remove the "Hard" need for Wedge Drivers.

John,
Could you give your exact definition of a iSCSI port.
Till your mails they were the definition of
- a "portal" (IP add),
- a SCSI service delivery port (=session end point from what i hearded in
Nashua)

It seems that you want to tie the  notion of SCSI service delivery port
to hardware, the opposite of what was presented in Nashua.

Do i miss something?

I see nothing wrong against SCSI or iSCSI to have two sessions (with 2 #
ISID) flowing from the same initiator adapter to the same target adapter.
Each session end point represents a SDP.

Regards,

Pierre


>
>
> OK, that's what I think our misunderstanding is all about.  If I am
> mistaken, please set me straight.
> .
> .
> .
> John L. Hufferd
> Senior Technical Staff Member (STSM)
> IBM/SSG San Jose Ca
> (408) 256-0403, Tie: 276-0403,  eFax: (408) 904-4688
> Internet address: hufferd@us.ibm.com
>
> Santosh Rao <santoshr@cup.hp.com>@cup.hp.com on 05/08/2001 05:44:41 PM
>
> Sent by:  santoshr@cup.hp.com
>
> To:   John Hufferd/San Jose/IBM@IBMUS
> cc:   Black_David@emc.com, ips@ece.cmu.edu
> Subject:  Re: iSCSI: multiple sessions b/n a pair of WWUIs.
>
> John,
>
> By the name-disc definition, an iSCSI initiator or target port is a
> logical entity that constitutes the end points of a session.
>
> Hence, there never can be 2 sessions b/n the *same* 2  initiator &
> target port. Each session established spawns a *new* initiator and
> target iSCSI port.
>
> Going by the above semantics, there is always only 1 ISID/TSID per iSCSI
> Initiator/Target port.
>
> Hence, I'm unable to understand your statements below.
>
> As for the uniqueness of ISID across all initiators, is there any reason
> not to allow implementations to do that ? I would have thought that is
> the most typical use of an ISID and also allows initiators to lookup
> their target structures based on ISID.
>
> Regards,
> Santosh
>
> John Hufferd wrote:
> >
> > Also, since a second session by the same iSCSI Initiator Port, to the
> same
> > iSCSI Target Port is not, in my opinion "legal", it is not clear to me
> that
> > any given iSCSI Port needs any more then one ISID.  I
> >
> > Therefore, I suggest that we Not put any such notes, like you suggest, in
> > the draft, but in fact encourage a single ISID/TSID per iSCSI
> > Initiator/Target Port.
>
> > To:   Jim Hafner/Almaden/IBM@IBMUS, marjorie_krueger@hp.com
> > cc:   ips@ece.cmu.edu
> > Subject:  RE: iSCSI: multiple sessions b/n a pair of WWUIs.
> >
> > While Jim's correct ... in Marj's defense, what
> > she wrote is a fairly obvious way to implement
> > it, and that might be worth noting in the draft.
> >
> > --David